U.S. Pat. No. 4,169,798 to DeMartino discusses the use of hydraulic fracturing fluid compositions to increase the productivity of oil and gas wells. The patentee notes that such hydraulic fracturing fluids commonly employ a viscosity increasing agent such as a water soluble polymer to improve the flow characteristics and the suspending ability of the fluids. The patentee provides hydraulic fracturing fluids which contain methylated derivatives of polygalactomannan gums as a gelling agent. These polygalactomannan derivatives are obtained by treating a natural gum, such as guar gum, with a methylating agent in the presence of a strongly alkaline compound in an amount sufficient to neutralize the strong acid which is generated in situ during the course of the methylation. The patentee states that the use of the natural gum derivatives results in improved viscosity and suspending properties of the hydraulic fracturing fluid compositions as well as a low yield of hydrolysis residue upon the subsequent hydrolysis of the polygalactomannan derivatives.
British Pat. No. 906,327 discloses that crushed guar seeds, wherein the seed is split but portions of the husk and embryo remain firmly adhered to the endosperm sections, can be treated with aqueous alkali at a temperature in the range of 60.degree. to 120.degree. C. to loosen the husks and embryos from the endosperm sections. The endosperm "splits" are obtained separate from the remaining husks and embryos of the seeds by centrifugation. The patentee does not disclose the use of an inert atmosphere nor does he discuss the viscosity of the galactomannan obtained thereby.
It is an object of the present invention to provide an improved process of refining gum splits by treatment with an aqueous alkaline solution.
It is an object of the present invention to provide hydraulic fracturing fluid compositions which contain alkali refined gum and which have high viscosity and low hydrolysis residue.
It is also an object of the present invention to provide a method of using such hydraulic fracturing fluid compositions.